1. Field
Example embodiments relate to power devices, and more particularly, to high electron mobility transistors and methods of manufacturing the same.
2. Description of the Related Art
In a power conversion system, an efficiency of the entire system may depend on an efficiency of a power switching device. As a switching device, a power metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) using silicon has been mainly used. However, increasing the efficiency of some switching devices may be limited due to material limitations of silicon.
To overcome the limitations of silicon material, research into a high electron mobility transistor (HEMT) is being actively conducted.
An HEMT may include semiconductor layers having different electrical polarization characteristics. A semiconductor layer having a relatively large polarizability in the HEMT may cause a two-dimensional electron gas (2DEG) in other semiconductor layers that are hetero-bonded with the semiconductor layer. The 2DEG may be used as a channel between a drain electrode and a source electrode, and an electric current flowing in the channel may vary according to a voltage applied to the drain and source electrodes.
To apply a voltage to the drain and source electrodes, the HEMT may include a drain pad and a source pad that electrically contact the drain electrode and the source electrode, respectively. To uniformly apply a voltage to the entire region of the drain electrode and the source electrode via the drain pad and the source pad, the areas of the drain and source pads may need to have at least a desired (and/or alternatively predetermined) area. In this regard, the areas of the drain pad and the source pad are determined by the widths and thicknesses of the pads.
For the areas of the drain and source pads to have at least a desired (and/or alternatively predetermined) area, there is a method of increasing the widths of the drain pad and the source pad. When the widths of the drain and source pads are increased, however, a length of a channel formed between the drain pad and the source pad becomes relatively small, or the entire size of the HEMT increases.